Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/1723`
 標題: 脈動流流經週期性凹槽渦流結構之數值探討Numerical Study of Vortex Structures in Pulsatile Flow through Periodically Grooved Channels 作者: 吳建村Wu, Jiann Tsuen 關鍵字: Pulsatile Flow;脈動流;Induced Frequency;Transport Phenomenon;誘發頻率;輸送現象 出版社: 機械工程學系 摘要: 本文主要目的是以數值模式研究低雷諾數之脈動流流經週期性凹槽流場之 渦漩結構、混合、質傳與熱傳之特性，並針對週期與振幅的影響加以探討 ，並以SIMPLE之數值運算模式來求解。假設流場為二維不可壓縮流流場， 入口流速為一具正弦波脈動之均勻流，當流場達週期性穩定狀態後，由流 場流線、u-v相圖及壁渦度梯度圖來分析流場的特性。 結果顯示，主 渦漩於流場減速時擴大，至零流速時，所有渦漩佔滿整個流場，此凹槽內 渦漩的動態行為產生混合、質傳與熱傳增強現象，而週期與振幅為引發這 種現象主要因子。此外，經流場頻譜分析發現，在振幅大於2.0、週期大 於5.0秒時，流場中出現異於脈動頻率之誘發頻率，此值為脈動頻率之倍 數。Vortex structure ,fluid mixing, mass and heat transfers characteristics in pulsatile flow through periodically grooved channels by numerical simulations are investigated at moderated Reynolds number. Two parameters , period and amplitude , are considered. A numerical scheme based on SIMPLE algorithm in this study. The flow is assumed to be two dimensional and incompressible. The inlet velocity is a uniform flow with sinusoidal pulsatile. The Streamlines ,u-v phase diagrams and wall vorticity gradient plot , The obtained results reveal that a primary vortex grows up during the deceleration phase for all conditions. At zero flow all vortices occupy the whole fluid domain. Mixing, mass and heat transfer enhancement are due to dynamic behavior of the vortex in the cavity. The factors of effect depend strongly on period and amplitude. We also find induced frequencies which is different from the pulsatile frequency in spectrum analysis when the period is more than 5.0 seconds and the amplitude is more than 2.0. URI: http://hdl.handle.net/11455/1723 Appears in Collections: 機械工程學系所